{ "data": { "question": { "questionId": "100305", "questionFrontendId": "剑指 Offer 36", "categoryTitle": "LCOF", "boundTopicId": 87118, "title": "二叉搜索树与双向链表 LCOF", "titleSlug": "er-cha-sou-suo-shu-yu-shuang-xiang-lian-biao-lcof", "content": "English description is not available for the problem. Please switch to Chinese.", "translatedTitle": "二叉搜索树与双向链表", "translatedContent": "

输入一棵二叉搜索树，将该二叉搜索树转换成一个排序的循环双向链表。要求不能创建任何新的节点，只能调整树中节点指针的指向。

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为了让您更好地理解问题，以下面的二叉搜索树为例：

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我们希望将这个二叉搜索树转化为双向循环链表。链表中的每个节点都有一个前驱和后继指针。对于双向循环链表，第一个节点的前驱是最后一个节点，最后一个节点的后继是第一个节点。

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下图展示了上面的二叉搜索树转化成的链表。“head” 表示指向链表中有最小元素的节点。

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特别地，我们希望可以就地完成转换操作。当转化完成以后，树中节点的左指针需要指向前驱，树中节点的右指针需要指向后继。还需要返回链表中的第一个节点的指针。

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注意：本题与主站 426 题相同：https://leetcode-cn.com/problems/convert-binary-search-tree-to-sorted-doubly-linked-list/

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注意：此题对比原题有改动。

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